Calibration for an instrument (device, sensor)

ABSTRACT

A device may determine a calibration value for a spectrometer using light from a first light source; deactivate the first light source after determining the calibration value; perform measurement with regard to a sample based on the calibration value, wherein the measurement of the sample is performed using light from a second light source; determine that the calibration value is to be updated; and update the calibration value using the light from the first light source.

RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.17/447,951, filed Sep. 17, 2021, which is a continuation of U.S. Pat.Application No. 16/879,856, filed May 21, 2020 (now U.S. Pat. No.11,137,288), which is a continuation of U.S. Pat. Application No.15/937,177, filed Mar. 27, 2018 (now U.S. Pat. No. 10,663,344), whichclaims priority under 35 U.S.C. § 119 to U.S. Provisional Pat.Application No. 62/490,445, filed on Apr. 26, 2017, the contents ofwhich are incorporated herein by reference in their entireties.

BACKGROUND

A spectrometer may perform transmission spectroscopy. In transmissionspectroscopy, light is passed through a sample and compared to lightthat has not been passed through the sample. This comparison may provideinformation based on the path length or sample thickness, the absorptioncoefficient of the sample, the reflectivity of the sample, the angle ofincidence, the polarization of the incident radiation, and, forparticulate matter, the particle size and orientation.

SUMMARY

According to some possible implementations, a method performed by adevice may include determining a calibration value for a spectrometerusing light from a first light source; deactivating the first lightsource after determining the calibration value; performing measurementof a sample based on the calibration value and after deactivating thefirst light source, wherein the measurement of the sample is performedusing light from a second light source; determining that the calibrationvalue is to be updated; activating the first light source based ondetermining that the calibration value is to be updated; and updatingthe calibration value using the light from the first light source afteractivating the first light source.

According to some possible implementations, a device may include amemory; and one or more processors coupled to the memory, the memory andthe one or more processors configured to: determine a calibration valuefor a spectrometer using light reflected from a first light source ofthe spectrometer to a sensor of the spectrometer, and wherein the lightis reflected from a diffuser of the spectrometer to the sensor;deactivate the first light source after determining the calibrationvalue; perform a measurement of a sample based on the calibration valueand after deactivating the first light source, wherein the measurementof the sample is performed using light from a second light source thatis received via the diffuser; determine that the calibration value is tobe updated; activate the first light source based on determining thatthe calibration value is to be updated; and update the calibration valueusing the light from the first light source after activating the firstlight source.

According to some possible implementations, a non-transitorycomputer-readable medium may store one or more instructions that, whenexecuted by one or more processors of a spectrometer, cause the one ormore processors to: determine a calibration value for the spectrometerusing light from a first light source; deactivate the first light sourceafter determining the calibration value; perform measurement with regardto a sample based on the calibration value and after deactivating thefirst light source, wherein the measurement of the sample is performedusing light from a second light source; determine that the calibrationvalue is to be updated; and update the calibration value using the lightfrom the first light source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are diagrams of an overview of an example implementationdescribed herein;

FIG. 2 is a diagram of an example environment in which systems and/ormethods, described herein, may be implemented;

FIG. 3 is a diagram of example components of one or more devices of FIG.2 ;

FIG. 4 is a diagram of an overview of a transmission spectrometerdescribed herein; and

FIG. 5 is a flow chart of an example process for determining a baselinecalibration value and calibrating a transmission spectrometer based onthe baseline calibration value.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements. The followingdescription uses a spectrometer as an example, however, the calibrationprinciples, procedures, and methods described herein may be used withany sensor, including but not limited to other optical sensors andspectral sensors.

Some spectral measurement applications may perform repetitive baselineor calibrating measurements to compensate for thermal and physicaleffects on the spectrometer sensor or hardware. Reducing the durationbetween these baseline or calibrating measurements reduces noise andincreases repeatability. However, many processes will not toleraterepeating the baseline or calibrating measurements more often than atthe start of the measurement period, which may last hours or days. Thecalibration process can be challenging for transmission measurementswhile actively measuring a process. For example, a process may bestopped and re-baselined using process material evacuated from thesample location. From a practicality standpoint, this can be challengingand frustrating to the end user.

Some implementations described herein may use a reference point, placedinto the measurement area, to perform baselining without needing to stopor impact the process. In some implementations, the reference point mayinclude a diffuser of the spectrometer, and the baseline calibrationvalue may be determined using an internal light source of thespectrometer (sometimes referred to herein as a spectrometer lightsource). In this way, a device, such as a spectrometer or another typeof device may be calibrated in a transmission mode as often as desiredto maintain a level of spectral performance appropriate for the enduser’s application. This may help mitigate effects of temperature on thesensor and may enable the use of sensors that were not previously chosenbecause of thermal limitations over time. Furthermore, someimplementations described herein may not use mechanical devices toperform such calibration. For example, some implementations describedherein may be monolithic and/or may use only the activation ordeactivation of light sources. Thus, calibration of the device that istransparent to the measurement process and that does not requireinterruption of manufacturing processes is achieved.

FIGS. 1A-1D are diagrams of an overview of an example implementation 100described herein. FIG. 1A shows an example of determination of adark-state baseline calibration value during a dark state of aspectrometer, wherein a spectrometer light source (e.g., a light sourceinternal to the spectrometer or provided between a sensor of thespectrometer and a diffuser of the spectrometer) and an external lightsource are deactivated. FIG. 1B shows an example of determination of alight-state baseline calibration, wherein the spectrometer light sourceis activated and the external light source is deactivated. FIG. 1C showsan example of measurement based on the light-state baseline calibration.Finally, FIG. 1D shows a determination of an updated light-statebaseline calibration value, which may be used to calibrate measurementsof the spectrometer. In FIGS. 1A-1D, a control device is not shown. Insome implementations, one or more of the operations described withregard to FIGS. 1A-1D may be performed by a control device. The controldevice may be separate from the spectrometer, may be included in thespectrometer, or may be associated with the spectrometer in anotherfashion.

FIG. 1A shows an example of a dark state of the spectrometer. As shownin FIG. 1A, and by reference number 105, in the dark state, aspectrometer light source (e.g., one or more lamps of the spectrometer)may be deactivated. As shown by reference number 110, an external lightsource associated with the spectrometer may be deactivated in the darkstate. As shown by reference number 115, the spectrometer may determinea dark-state baseline calibration value. For example, the spectrometermay determine the dark-state baseline calibration while both lightsources are deactivated. In this way, a dark-state baseline calibrationvalue is determined without the use of moving parts, such as mechanicalflags and/or the like.

FIG. 1B shows an example of determination of a light-state baselinecalibration value for the spectrometer. As shown in FIG. 1B, and byreference number 120, the spectrometer light source may be activated fordetermination of the light-state baseline calibration value. In such acase, light from the spectrometer light source may reflect off adiffuser 125 to present repeatable light conditions for determination ofthe light-state baseline calibration value. As shown by reference number130, the external light source may be deactivated for determination ofthe light-state baseline calibration value. As shown by reference number135, the spectrometer may determine the light-state baseline calibrationvalue based on the spectrometer light source (e.g., based on thereflection of the spectrometer light source from the diffuser 125). Thismay provide a repeatable method to perform relative baselines withoutthe use of moving parts, stopping a manufacturing or measurementprocess, cleaning a measurement system, or accessing difficult-to-reachmeasurement locations. Additionally, or alternatively, this process mayprovide increased accuracy of measurements because calibration can occurmany times a minute if needed to compensate for a thermally variableenvironment.

In some implementations, the spectrometer may activate the externallight source in addition to the spectrometer light source to determinethe light-state baseline calibration value. This may provide forbaselining based on relative spectral measurements using the externallight source and the spectrometer light source. In some implementations,the spectrometer may activate the spectrometer light source and not theexternal light source to determine the light-state baseline calibrationvalue. This may conserve energy and simplify determination of thelight-state baseline calibration value.

FIG. 1C shows an example of performing measurement based on a baselinecalibration value. As shown in FIG. 1C, and by reference number 140, thespectrometer may deactivate the spectrometer light source. As shown byreference number 145, the spectrometer may activate the external lightsource. As shown, the external light source may provide light through alens (e.g., an aspheric lens) to sample windows (e.g., a cuvette, etc.).The sample to be measured may be provided between the sample windows.The light may interact with the sample and may continue to the diffuser.The diffuser may diffuse the light for measurement by a sensor of thespectrometer (not shown). The spectrometer may perform the measurementbased on a baseline calibration value, such as the dark-state baselinecalibration value and/or the light-state baseline calibration value. Forexample, the spectrometer may determine an adjustment for themeasurement based on the baseline calibration value.

FIG. 1D shows an example of updating a baseline calibration value usingthe light-state baseline calibration technique. As shown by referencenumber 150, the spectrometer may determine to update the light-statebaseline calibration value. In some implementations, the spectrometermay perform the update periodically (e.g., at a predefined interval). Insome implementations, the spectrometer may perform the update based on athreshold, such as a threshold temperature change, a threshold number ofmeasurements, and/or the like.

As shown by reference number 155, the spectrometer may activate thespectrometer light source to determine the updated light-state baselinecalibration value. For example, the spectrometer may activate thespectrometer light source to reflect light that originates from thespectrometer light source off of the diffuser and back to the sensor.The spectrometer may determine the updated light-state baselinecalibration value based on the reflected light. In this way, thespectrometer updates the baseline calibration value without using movingparts, such as mechanical flags and/or the like, to perform thecalibration.

As shown by reference number 160, the spectrometer may deactivate theexternal light source to update the light-state baseline calibrationvalue. In some implementations, the spectrometer may determine thelight-state baseline calibration value while the external light sourceis activated, as described in more detail in connection with FIG. 1B,above.

In this way, a transmission spectrometer may be calibrated using aspectrometer light source to maintain a level of spectral performanceappropriate for an end user’s application. This may help mitigateeffects of temperature on the sensor and may enable the use of sensorsthat were not previously chosen because of thermal limitations overtime. Furthermore, some implementations described herein may not usemechanical devices with moving parts, such as a calibration flag, toperform such calibration. For example, some implementations describedherein may be monolithic and/or may use only the activation ordeactivation of light sources and measurement components of thespectrometer. Thus, calibration of the spectrometer that is transparentto the measurement process and that does not require interruption ofmanufacturing processes is achieved.

As indicated above, FIGS. 1A-1D are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 1A-1D. For example, the operations described in FIGS. 1A-1D maybe performed for a device other than a spectrometer.

FIG. 2 is a diagram of an example environment 200 in which systemsand/or methods, described herein, may be implemented. As shown in FIG. 2, environment 200 may include a control device 210, a spectrometer 220,and a network 230. Devices of environment 200 may interconnect via wiredconnections, wireless connections, or a combination of wired andwireless connections.

Control device 210 includes one or more devices capable of storing,processing, and/or routing information associated with spectroscopiccalibration. For example, control device 210 may include a server, acomputer, a wearable device, a cloud computing device, and/or the like.In some implementations, control device 210 may store, process, and/ordetermine information associated with a baseline of spectrometer 220. Insome implementations, control device 210 may calibrate spectrometer 220and/or determine a measurement based on the baseline of spectrometer220. In some implementations, control device 210 may be associated witha particular spectrometer 220. In some implementations, control device210 may be associated with multiple spectrometers 220. In someimplementations, control device 210 may be a component of spectrometer220. In some implementations, control device 210 may receive informationfrom and/or transmit information to another device in environment 200,such as spectrometer 220.

Spectrometer 220 includes one or more devices capable of performing aspectroscopic measurement on a sample. For example, spectrometer 220 mayinclude a spectrometer device that performs spectroscopy (e.g.,vibrational spectroscopy, such as a near infrared (NIR) spectrometer, amid-infrared spectroscopy (mid-IR), Raman spectroscopy, and/or thelike). In some implementations, spectrometer 220 may include atransmission spectrometer, as described in more detail in connectionwith FIG. 4 , below. In some implementations, spectrometer 220 may beincorporated into a wearable device, such as a wearable spectrometerand/or the like. In some implementations, spectrometer 220 may receiveinformation from and/or transmit information to another device inenvironment 200, such as control device 210.

Network 230 may include one or more wired and/or wireless networks. Forexample, network 230 may include a cellular network (e.g., a long-termevolution (LTE) network, a 3G network, a code division multiple access(CDMA) network, etc.), a public land mobile network (PLMN), a local areanetwork (LAN), a wide area network (WAN), a metropolitan area network(MAN), a telephone network (e.g., the Public Switched Telephone Network(PSTN)), a private network, an ad hoc network, an intranet, theInternet, a fiber optic-based network, a cloud computing network, and/orthe like, and/or a combination of these or other types of networks.

The number and arrangement of devices and networks shown in FIG. 2 areprovided as an example. In practice, there may be additional devicesand/or networks, fewer devices and/or networks, different devices and/ornetworks, or differently arranged devices and/or networks than thoseshown in FIG. 2 . Furthermore, two or more devices shown in FIG. 2 maybe implemented within a single device, or a single device shown in FIG.2 may be implemented as multiple, distributed devices. Additionally, oralternatively, a set of devices (e.g., one or more devices) ofenvironment 200 may perform one or more functions described as beingperformed by another set of devices of environment 200.

FIG. 3 is a diagram of example components of a device 300. Device 300may correspond to a control device 210 and/or a spectrometer 220. Insome implementations control device 210 and/or a spectrometer 220 mayinclude one or more devices 300 and/or one or more components of device300. As shown in FIG. 3 , device 300 may include a bus 310, a processor320, a memory 330, a storage component 340, an input component 350, anoutput component 360, and a communication interface 370.

Bus 310 includes a component that permits communication among thecomponents of device 300. Processor 320 is implemented in hardware,firmware, or a combination of hardware and software. Processor 320 is acentral processing unit (CPU), a graphics processing unit (GPU), anaccelerated processing unit (APU), a microprocessor, a microcontroller,a digital signal processor (DSP), a field-programmable gate array(FPGA), an application-specific integrated circuit (ASIC), or anothertype of processing component. In some implementations, processor 320includes one or more processors capable of being programmed to perform afunction. Memory 330 includes a random access memory (RAM), a read onlymemory (ROM), and/or another type of dynamic or static storage device(e.g., a flash memory, a magnetic memory, and/or an optical memory) thatstores information and/or instructions for use by processor 320.

Storage component 340 stores information and/or software related to theoperation and use of device 300. For example, storage component 340 mayinclude a hard disk (e.g., a magnetic disk, an optical disk, amagneto-optic disk, and/or a solid state disk), a compact disc (CD), adigital versatile disc (DVD), a floppy disk, a cartridge, a magnetictape, and/or another type of non-transitory computer-readable medium,along with a corresponding drive.

Input component 350 includes a component that permits device 300 toreceive information, such as via user input (e.g., a touch screendisplay, a keyboard, a keypad, a mouse, a button, a switch, and/or amicrophone). Additionally, or alternatively, input component 350 mayinclude a sensor for sensing information (e.g., a global positioningsystem (GPS) component, an accelerometer, a gyroscope, and/or anactuator). Output component 360 includes a component that providesoutput information from device 300 (e.g., a display, a speaker, and/orone or more light-emitting diodes (LEDs)).

Communication interface 370 includes a transceiver-like component (e.g.,a transceiver and/or a separate receiver and transmitter) that enablesdevice 300 to communicate with other devices, such as via a wiredconnection, a wireless connection, or a combination of wired andwireless connections. Communication interface 370 may permit device 300to receive information from another device and/or provide information toanother device. For example, communication interface 370 may include anEthernet interface, an optical interface, a coaxial interface, aninfrared interface, a radio frequency (RF) interface, a universal serialbus (USB) interface, a Wi-Fi interface, a cellular network interface, orthe like.

Device 300 may perform one or more processes described herein. Device300 may perform these processes based on processor 320 executingsoftware instructions stored by a non-transitory computer-readablemedium, such as memory 330 and/or storage component 340. Acomputer-readable medium is defined herein as a non-transitory memorydevice. A memory device includes memory space within a single physicalstorage device or memory space spread across multiple physical storagedevices.

Software instructions may be read into memory 330 and/or storagecomponent 340 from another computer-readable medium or from anotherdevice via communication interface 370. When executed, softwareinstructions stored in memory 330 and/or storage component 340 may causeprocessor 320 to perform one or more processes described herein.Additionally, or alternatively, hardwired circuitry may be used in placeof or in combination with software instructions to perform one or moreprocesses described herein. Thus, implementations described herein arenot limited to any specific combination of hardware circuitry andsoftware.

The number and arrangement of components shown in FIG. 3 are provided asan example. In practice, device 300 may include additional components,fewer components, different components, or differently arrangedcomponents than those shown in FIG. 3 . Additionally, or alternatively,a set of components (e.g., one or more components) of device 300 mayperform one or more functions described as being performed by anotherset of components of device 300.

FIG. 4 is a diagram of an overview of components of a transmissionspectrometer system 400 described herein. As shown, transmissionspectrometer system 400 may include a sensor 410, a spectrometer lightsource 420, a diffuser 430, process windows 440, an external lightsource 450, and/or a lens 460. In some implementations, transmissionspectrometer system 400 may include control device 210 and/orspectrometer 220.

Sensor 410 includes a sensor to perform spectroscopy with regard to asample based on light transmitted via the sample (e.g., lighttransmitted by external light source 450). In some implementations,sensor 410 may receive light generated by spectrometer light source 420,such as light reflected by diffuser 430. In some implementations, sensor410 may perform measurement based on a calibration value (e.g., alight-state and/or dark-state baseline calibration value).

Spectrometer light source 420 includes one or more lamps of transmissionspectrometer system 400. Spectrometer light source 420 may generatelight to be used for determination of a light-state baseline calibrationvalue. The light generated by spectrometer light source 420 may reflectoff diffuser 430 and back to sensor 410. By using spectrometer lightsource 420 to perform light-state calibration, a flow associated with asample (e.g., a sample flowing between process windows 440) need not beinterrupted. This may increase the frequency of baselining, therebyimproving measurement accuracy and enabling the use of transmissionspectrometer system 400 in more variable temperature conditions.

Diffuser 430 includes a component that diffuses light reflected ortransmitted via diffuser 430. In some implementations, diffuser 430 mayprevent or reduce spatial or spectral content (e.g., parasitic ornoncoherent spectral features) of light provided to sensor 410. In someimplementations, diffuser 430 may include polytetrafluoroethylene(PTFE), which may reduce a cost of diffuser 430 in comparison to othermaterials. In some implementations, diffuser 430 may include anothermaterial, such as polystyrene, which may increase a spectral range ofdiffuser 430. In some implementations, diffuser 430 may include aholographic diffuser, a frosted surface, and/or the like. In someimplementations, diffuser 430 may be located between approximately 2 mmand approximately 5 mm from a nearest process window of process windows440.

Process windows 440 may partially or completely enclose a sample forwhich transmission spectroscopy is to be performed using external lightsource 450. For example, process windows 440 may include a cuvette or asimilar enclosure (e.g., an optically clear container for holding liquidsamples). In some implementations, process windows 440 may enclose aflowing sample. For example, the sample to be measured by transmissionspectrometer system 400 may be in a flowing state. In such a case, theability to perform baseline calibration using spectrometer light source420 may be particularly valuable, since it may be expensive andundesirable to interrupt the flowing state of the sample.

External light source 450 includes one or more lamps for performingtransmission spectrometry of the sample. In some implementations,external light source 450 may be included in transmission spectrometersystem 400. In some implementations, external light source 450 may beseparate from transmission spectrometer system 400. In someimplementations, external light source 450 may be controlled by acontrol device (e.g., control device 210) and/or a spectrometer (e.g.,spectrometer 220, transmission spectrometer system 400, etc.). Lightgenerated by external light source 450 may transmit via a lens 460(e.g., an aspheric lens) through the sample within process windows 440.Lens 460 may focus and/or collimate the light from external light source450. The light generated by external light source 450 may be diffused bydiffuser 430, and may be sensed by sensor 410. Transmission spectrometersystem 400 (e.g., and/or a control device associated with transmissionspectrometer system 400) may determine a measurement based on the lightgenerated by external light source 450 and based on a light-statebaseline calibration value determined using the spectrometer lightsource 420. In some implementations, external light source 450 mayinclude a solid light pipe, shown as a hatched cylinder.

The number and arrangement of components shown in FIG. 4 are provided asan example. In practice, transmission spectrometer system 400 mayinclude additional components, fewer components, different components,or differently arranged components than those shown in FIG. 4 .Additionally, or alternatively, a set of components (e.g., one or morecomponents) of transmissions spectrometer 400 may perform one or morefunctions described as being performed by another set of components oftransmission spectrometer system 400.

FIG. 5 is a flow chart of an example process 500 for determining abaseline calibration value and calibrating a transmission spectrometerbased on the baseline calibration value. In some implementations, one ormore process blocks of FIG. 5 may be performed by control device 210. Insome implementations, one or more process blocks of FIG. 5 may beperformed by another device or a group of devices separate from orincluding control device 210, such as spectrometer 220 or a differentdevice.

As shown in FIG. 5 , process 500 may include determining a firstbaseline calibration value while an external light source and aspectrometer light source are not activated (block 510). For example,control device 210 (e.g., using processor 320, communication interface370, and/or the like) may determine a first baseline calibration valuewhile an external light source (e.g., external light source 450) and aspectrometer light source (e.g., spectrometer light source 420) are notactivated. In some implementations, the first baseline calibration valuemay be a dark-state baseline calibration value. Control device 210 mayuse the first baseline calibration value and a second baselinecalibration value (described below) to perform measurement of a sample,as described in more detail below.

As further shown in FIG. 5 , process 500 may include determining asecond baseline calibration value while the spectrometer light source isactivated (block 520). For example, control device 210 (e.g., usingprocessor 320, communication interface 370, and/or the like) maydetermine a second baseline calibration value while the spectrometerlight source is activated. The second baseline calibration value may bethe light-state baseline calibration value, described elsewhere herein.In some implementations, control device 210 may determine the secondbaseline calibration value while the external light source isdeactivated, as described in more detail elsewhere herein. Additionally,or alternatively, control device 210 may determine the second baselinecalibration value while the external light source is activated, as isalso described in more detail elsewhere herein. Control device 210 maydetermine the second baseline calibration value using light that isreflected from a reference point of spectrometer 220, such as a diffuser430 of transmission spectrometer system 400 or spectrometer 220, whichreduces or eliminates the need for mechanical components for baselining,such as baselining flags and/or the like. Thus, baselining may beperformed without operation of a mechanical component of thespectrometer, such as a mechanical flag or a similar reference point forcalibration.

As further shown in FIG. 5 , process 500 may include performingmeasurement based on the first baseline calibration value and/or thesecond baseline calibration value (block 530). For example, controldevice 210 (e.g., using processor 320, communication interface 370,and/or the like) may perform measurement using a sensor (e.g., sensor410) of the spectrometer by activating the external light source (e.g.,and allowing the external light source to stabilize). Control device 210may perform the measurement based on the first baseline calibrationvalue and/or the second baseline calibration value. For example, whencontrol device 210 has determined a dark-state baseline calibrationvalue and a light-state baseline calibration value, control device 210may use the dark-state baseline calibration value and the light-statebaseline calibration value to perform the measurement. When controldevice 210 has determined a light-state baseline calibration value andnot a dark-state baseline calibration value, control device 210 mayperform the measurement using the light-state baseline calibrationvalue. In some implementations, control device 210 may deactivate thespectrometer light source to perform the measurement, which may reduceinterference with the measurement due to light from the spectrometerlight source.

As further shown in FIG. 5 , process 500 may include determining thatthe second baseline calibration value is to be updated (block 540). Forexample, control device 210 (e.g., using processor 320, communicationinterface 370, and/or the like) may determine that the second baselinecalibration value (e.g., the light-state baseline calibration value) isto be updated. In some implementations, control device 210 may determinethat the second baseline calibration value is to be updated based on athreshold, such as a threshold temperature change, a threshold length oftime since a last update to the second baseline calibration value, athreshold deviation of a measurement from an expected or previous value,and/or the like. In some implementations, control device 210 maydetermine that the second baseline calibration value is to be updatedbased on an input, such as a user input to trigger the updating of thesecond baseline calibration value.

As further shown in FIG. 5 , process 500 may include activating thespectrometer light source, and updating the second baseline calibrationvalue while the spectrometer light source is activated (block 550, andreturning to block 520). For example, control device 210 (e.g., usingprocessor 320, communication interface 370, and/or the like) may havedeactivated the spectrometer light source to perform the measurement ofthe sample. Control device 210 may reactivate the spectrometer lightsource to update the second baseline calibration value. For example,control device 210 may reactivate the spectrometer light source so thatlight from the spectrometer light source reflects from the diffuser tothe sensor, thereby enabling baselining of spectrometer 220 withoutusing mechanical means such as baselining flags, which reduces expenseof measurement and enables the implementation of the spectrometer inhard-to-reach places, which may have been hampered by concerns aboutaccessibility of the spectrometer for resolving issues with themechanical means. Further, updating baselining using the spectrometerlight source may require less interruption (or no interruption) of aflow state of the sample to be measured, which may reduce expense andincrease the viable frequency of baselining. This, in turn, may enablethe use of the spectrometer in more variable temperature conditions thana spectrometer that is not capable of performing baselining asfrequently.

Although FIG. 5 shows example blocks of process 500, in someimplementations, process 500 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 5 . Additionally, or alternatively, two or more of theblocks of process 500 may be performed in parallel.

In this way, a transmission spectrometer (e.g., spectrometer 220 ortransmission spectrometer system 400) may be calibrated using aspectrometer light source (e.g., spectrometer light source 420) tomaintain a level of spectral performance appropriate for an end user’sapplication. This may help mitigate effects of temperature on the sensor(e.g., sensor 410) and may enable the use of sensors that were notpreviously chosen because of thermal limitations over time. Furthermore,some implementations described herein may not use mechanical componentsto perform such calibration. For example, some implementations describedherein may be monolithic and/or may use only the activation ordeactivation of light sources (e.g., spectrometer light source 420and/or external light source 450). Thus, calibration of the spectrometerthat is transparent to the measurement process and that does not requireinterruption of manufacturing processes is achieved.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise form disclosed. Modifications and variations are possible inlight of the above disclosure or may be acquired from practice of theimplementations.

Some implementations are described herein in connection with thresholds.As used herein, satisfying a threshold may refer to a value beinggreater than the threshold, more than the threshold, higher than thethreshold, greater than or equal to the threshold, less than thethreshold, fewer than the threshold, lower than the threshold, less thanor equal to the threshold, equal to the threshold, or the like.

It will be apparent that systems and/or methods, described herein, maybe implemented in different forms of hardware, firmware, or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the implementations. Thus, the operation and behaviorof the systems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based on thedescription herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of possible implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of possible implementations includes each dependent claim incombination with every other claim in the claim set.

As used herein, the term “or” is meant to mean (or be the equivalent of)“and/or,” unless otherwise stated. In other words, as used herein, theterm “or” is an inclusive “or,” unless explicitly stated otherwise(e.g., when “or” is used in combination with “either one of”).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items(e.g., related items, unrelated items, a combination of related andunrelated items, etc.), and may be used interchangeably with “one ormore.” Where only one item is intended, the term “one” or similarlanguage is used. Also, as used herein, the terms “has,” “have,”“having,” or the like are intended to be open-ended terms. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

What is claimed is:
 1. A system comprising: one or more light sourcesconfigured to be deactivated during a dark state; a spectrometerconfigured to determine a dark-state baseline calibration value duringthe dark state; and a diffuser configured to diffuse light, thespectrometer being further configured to perform a measurement based onthe light and based on the dark-state baseline calibration value.
 2. Thesystem of claim 1, wherein the one or more light sources include: aspectrometer light source, and an external light source associated withthe spectrometer.
 3. The system of claim 2, wherein the spectrometerlight source includes one or more lamps of the spectrometer.
 4. Thesystem of claim 2, wherein the dark-state baseline calibration value isdetermined while the spectrometer light source and the external lightsource are deactivated.
 5. The system of claim 1, wherein the dark-statebaseline calibration value is determined without use of moving parts. 6.The system of claim 1, wherein the one or more light sources include aspectrometer light source, and wherein the spectrometer is furtherconfigured to determine a light-state baseline calibration value whilethe spectrometer light source is activated.
 7. The system of claim 6,wherein, to determine the light-state baseline calibration value, thespectrometer is configured to determine the light-state baselinecalibration value based on a reflection of the spectrometer light sourcefrom the diffuser.
 8. The system of claim 1, wherein the one or morelight sources include an external light source associated with thespectrometer, and wherein the spectrometer is further configured todetermine a light-state baseline calibration value while the externallight source is deactivated.
 9. The system of claim 1, wherein thediffuser includes polytetrafluoroethylene (PTFE).
 10. The system ofclaim 1, further comprising: one or more process windows configured topartially or completely enclose a sample.
 11. The system of claim 10,wherein the diffuser is located between approximately 2 millimeters (mm)and approximately 5 mm from a process window of the one or more processwindows.
 12. The system of claim 1, wherein the one or more lightsources include: a spectrometer light source, and an external lightsource associated with the spectrometer, and wherein the spectrometer isfurther configured to deactivate the spectrometer light source andactivate the external light source before performing the measurement.13. The system of claim 1, wherein the measurement is performed furtherbased on a light-state baseline calibration value.
 14. The system ofclaim 1, further comprising: a control device, wherein, to perform themeasurement, the control device is configured to perform the measurementusing a sensor of the spectrometer by activating an external lightsource of the one or more light sources and allowing the external lightsource to stabilize.
 15. A system comprising: one or more light sourcesconfigured to be deactivated during a dark state; and a spectrometerconfigured to determine a dark-state baseline calibration value duringthe dark state.
 16. The system of claim 15, further comprising: adiffuser configured to diffuse light.
 17. The system of claim 15,wherein the spectrometer is further configured to perform a measurementbased on the dark-state baseline calibration value.
 18. A systemcomprising: a spectrometer configured to determine a dark-state baselinecalibration value during a dark state; and a diffuser configured todiffuse light, the spectrometer being further configured to perform ameasurement based on one or more of the light or the dark-state baselinecalibration value.
 19. The system of claim 18, wherein the dark-statebaseline calibration value is determined while a light source isdeactivated.
 20. The system of claim 18, wherein the dark-state baselinecalibration value is determined without use of moving parts.